The present invention relates to a magneto-optical disk drive, and more particularly to a magneto-optical disk drive in which an electromagnet for an optical head is formed as a plurality of subdivided electromagnet components, and the magnetic fields from the respective subdivided electromagnet components are concentrated to obtain a desired intensity of the magnetic force, and at the same time the respective LC time constants are lowered, thereby enabling high-speed data processing.
In a general magneto-optical disk player, laser light is illuminated on a recording layer of a medium which rotates by a driving apparatus. Accordingly, the recording layer of the medium is heated so that magnetization of the recording layer can be inverted. At the same time, a strong magnetic field coming from a separately provided electromagnet passes through a recording surface. Accordingly, recording is performed according to a discriminative local magnetic field direction of the recording medium.
In this case, an inverted signal of the magnetic field is considerably lower than that of the non-inverted signal to be recorded. Thus, if a signal should be recorded over the signal previously recorded on the medium, the previously recorded data is erased, to then record the desired data. Therefore, during recording, a predetermined time interval is required to erase the previously recorded data.
To solve the above problem, a number of over-writing methods have been proposed. In such conventional magneto-optical disk players, as shown in FIGS. 1 and 2, laser light 31 from a laser head 3 provided below a medium 5 rotated by a driver 4, illuminates a recording layer 53 of the medium. Accordingly, recording layer 53 of medium 5 is heated so as to invert its magnetization-inverted. Simultaneously, a strong magnetic field from electromagnet 1 is provided above medium 5 passes through recording layer 53. Accordingly, the induced discriminative local magnetic field direction of recording layer 53 is established. Electromagnet I is fixed to a sleigh-shaped slider 2, so that electromagnet 1 can be reciprocated by a predetermined distance along the surface of recording layer 53. Electromagnet 1 is applied with a high-frequency signal. To reduce the time constant of the electromagnet due to the high-frequency drive of the magneto-optical disk drive having such an over-writing structure, the electromagnet should be installed as close as possible to the recording surface of the medium. Generally, the depth of protection layers 51 and 52 for protecting the recording layer of the medium is in the neighborhood of several micrometers. On the other hand, the distance between the front end of slider 2 and recording layer 53 of medium 5 which are opposed to each other should be kept at 10 to 20 .mu.m.
However, the magneto-optical disk drive having such an over-writing method has two significant drawbacks.
Firstly, considering the aforementioned distance between slider 2 and the surface of medium 5, the use of such an over-writing method is difficult in operational circumstances in which foreign matter such as hair, dust, etc., exists. Also, due to magnetic friction between slider 2 and medium 5, the surface of protecting layers 51 can be easily damaged.
Secondly, a transparent protecting layer 54 having a thickness of 1.2 mm should be formed on the side which receives the laser beam which is incident to the upper portion of recording layer 53. However, for double-sided recording on medium 5, the distance between electromagnet 1 and recording layer 53 becomes increased due to the combined thickness of protecting layers 51 and 52. Accordingly, the formation of a magnetic field having the necessary intensity is difficult. Thus,in the conventional method, only a single-sided medium can be used, resulting in reducing the recording capabilities of the medium.